1. Field of the Invention
The present invention relates to a facility for checking or, respectively, for correcting color pictures on a color monitor according to the preamble of patent claim 1.
2. Description of the Prior Art
A color viewing device with which an image to be printed can be displayed, corrected and evaluated is already disclosed by the DE-AS No. 26 07 623 (U.S. Pat. No. 4,285,009). U.S. Pat. No. 4,393,399 corresponds to PCT-OS No. 80/02607 U.S. Pat. Nos. 4,285,009 and 4,393,399 are hereby incorporated by reference. Extensive image corrections can be undertaken with this apparatus and therewith achieved is that the picture displayed on the color monitor and potentially corrected comes as close as possible to the final printing result, i.e. to the picture as it later appears when printed. An objective image evaluation is required for this purpose. This is only possible when the operator, in addition to the more or less subjective visual image impression, has possibilities which allow binding, reproducible statements. Measuring the colors is, for example, such a means. A cursor mixed into the image is thereby moved to the picture detail to be measured and the corresponding color values are read at, for example, a measuring instrument or these color values are mixed in at the margin of the picture. The corresponding printing ink for these color values can then be identified in a color atlas and this reference color is compared to the picture screen. This method is not optimum since it is time-intensive and not reliable in evaluation, for the eye becomes insensitive given a greater distance between the colors to be evaluated or, respectively, compared.
Further, errors can occur due to unfavorable lighting and a colored surround field of the color to be evaluated.
Further known in the evaluation of color pictures is to make reference colors visible on the color monitor at the margin of the picture. This type of evaluation is likewise still faulty since the chromatic impression of the picture element to be evaluated or of the picture detail to be evaluated is influenced by the surrounding colors and there is a distance from the reference color fields.